There's no advice more helpful than the age-old "Read a lot, write a lot" maxim, but if I had to add something to that, I'd add "write broadly"; that is to say, if your goal is to better your craft, I think you'll get far more mileage out of writing 25 short stories than you would one epic novel. A mistake I see too many aspiring writers make is falling in love with their first idea and then spending a decade iterating on the same 650k word fantasy epic, coming away with unsellable book and far too little skillset gain. I feel great about selling this novel, but the road to selling it was composed of at least 20 short stories that didn't sell and three unsold novels. I regret none of it; each failure teaches you something you'll need to succeed, which is why I think it's important, especially when you're learning, to fail early and fail often.

Adding to that, if at all possible, I'd recommend pushing yourself out of your comfort zone and reading/writing different genres, especially ones you don't normally follow. When you stick to just your familiar genres, it's very easy to occupy yourself with tropes and cliches, but when you're in unfamiliar waters, you have to really learn the basics of good storytelling. I used to write only adult horror and scifi until I got a job writing episodic teen romance which was wildly out of my comfort zone, but doing it taught me so much more about storytelling than if I'd written yet another werewolf story, because I had to learn how to do things like character-driven plots, witty banter, romantic tension, etc.

So, yeah. Read a lot. Write a lot. Experiment a lot. Fail a lot. And know that it's a long hard road with a lot of valleys of despair and hopelessness, but holy shit is reaching that peak ever worth it.